Pre-treatment with oral hydroxyurea prior to intensive chemotherapy improves early survival of patients with high hyperleukocytosis in acute myeloid leukemia

Outcomes of Elderly Patients Admitted to the Intensive Care Unit for Newly Diagnosed Acute Myeloid Leukemia

Acute myeloid leukemias (AMLs) are the hematological malignancies with the highest need for intensive care unit (ICU) admission due to their association with various life-threatening situations. Limited data exist regarding the outcomes of elderly individuals with AML admitted to the ICU. However, current therapeutic protocols offer the potential for extended survival in this population. This retrospective, monocentric study focused on the outcomes of individuals aged ≥ 60 years admitted to the ICU for newly diagnosed AML. It included 139 patients admitted to the ICU at the Paoli-Calmettes Institute between April 2010 and October 2020, during the initial phase of AML management. Patients were categorized into three groups based on the presence of biological criteria indicating "high risk" for complications (thrombocytopenia < 50 000/mm3 and leukocytosis > 50 000/mm3) and organ failure. Multiple logistic regression models were employed to identify predictive factors for in-hospital and day 90 mortality, while Cox regression was used for 1-year mortality. The rates of in-hospital, day 90, and 1-year mortality were 37%, 42%, and 60%, respectively. Variables associated with in-hospital mortality included the Charlson Comorbidity Index, the need for invasive mechanical ventilation (MV), and multi-organ failure. ELN17 risk was significantly associated with 1-year mortality rates. This study demonstrates the benefits of ICU management for individuals aged ≥ 60 years during the initial phase of AML. It illustrates the effects of age, comorbidities, and the severity of organ failures on short-term mortality and highlights the impact of classical prognostic markers on long-term mortality.

Emergencies in Hematology: Why, When and How I Treat?

Hematological emergencies are critical medical conditions that require immediate attention due to their rapid progression and life-threatening nature. As various examples, hypercalcemia, often associated with cancers such as multiple myeloma, can lead to severe neurological and cardiac dysfunction. Hyperleukocytosis, common in acute myeloid leukemias, increases the risk of leukostasis and multiorgan failure. Sickle cell crisis, a common complication in sickle cell disease, results from vaso-occlusion, leading to acute pain and tissue ischemia. Tumor lysis syndrome, reported in cases of rapid destruction of cancer cells, causes electrolyte imbalances and acute kidney injury. Acute transfusion reactions, fundamental in hematological conditions, can range from mild allergic responses to severe hemolysis and shock, requiring prompt management. Disseminated intravascular coagulation, involving excessive coagulation and bleeding, is commonly triggered by hematological malignancies, common in the first phases of acute promyelocytic leukemia. Recently, in the era of bispecific antibodies and chimeric antigen receptor T cells, cytokine release syndrome is a manifestation that must be recognized and promptly treated. Understanding the pathophysiology, recognizing the clinical manifestations, and ensuring adequate diagnostic strategies and management approaches for each condition are central to early intervention in improving patient outcomes and reducing mortality.

Acute respiratory failure in adult patients with acute myeloid leukemia

INTRODUCTION

Patients with acute myeloid leukemia (AML) are at high risk of developing life-threatening complications. It is estimated that a quarter of adult patients diagnosed with AML will require admission to the intensive care unit (ICU) at least once during their disease. Acute respiratory failure (ARF) is the main reason for ICU admission and is associated with high mortality rates, depending on the etiology of ARF.

AREAS COVERED

In this population, the high prevalence of severe pulmonary infections highlights the importance of immunosuppression caused by the disease and its treatment. In the early stages of the disease, in addition to pneumonia, which should be systematically sought, leukemia-specific lung involvement (leukostasis, leukemic pulmonary infiltration, and acute lysis pneumopathy) is an important cause of ARF in this population, representing up to 60% of cases. This review aims to help understand the pathophysiology and management of leukemia-specific lung involvement, based on the most contemporary literature.

EXPERT OPINION

The number of AML patients requiring ICU care is expected to increase. AML patients admitted to the ICU for ARF have a high mortality rate, but survivors have encouraging long-term outcomes. Future research will focus on improving risk stratification, cytoreduction, oxygenation strategies, and diagnostic techniques for ARF.

Management of hematological patients requiring emergency chemotherapy in the intensive care unit

Hematological malignancies may require rapid-onset treatment because of their short doubling time, notably observed in acute leukemias and specific high-grade lymphomas. Furthermore, in targeted onco-hematological scenarios, chemotherapy is deemed necessary as an emergency measure when facing short-term, life-threatening complications associated with highly chemosensitive hematological malignancies. The risks inherent in the disease itself, or in the initiation of treatment, may then require admission to the intensive care unit (ICU) to optimize monitoring and initial management protocols. Hyperleukocytosis and leukostasis in acute leukemias, tumor lysis syndrome, and disseminated intravascular coagulation are the most frequent onco-hematological complications requiring the implementation of emergency chemotherapy in the ICU. Chemotherapy must also be started urgently in secondary hemophagocytic lymphohistiocytosis. Tumor-induced microangiopathic hemolytic anemia and plasma hyperviscosity due to malignant monoclonal gammopathy represent infrequent yet substantial indications for emergency chemotherapy. In all cases, the administration of emergency chemotherapy in the ICU requires close collaboration between intensivists and hematology specialists. In this review, we provide valuable insights that aid in the identification and treatment of patients requiring emergency chemotherapy in the ICU, offering diagnostic tools and guidance for their overall initial management.

How I manage acute respiratory failure in patients with hematological malignancies

ABSTRACT

Acute respiratory failure (ARF) is common in patients with hematological malignancies notably those with acute leukemia, myelodysplastic syndrome, or allogeneic stem cell transplantation. ARF is the leading reason for intensive care unit (ICU) admission, with a 35% case fatality rate. Failure to identify the ARF cause is associated with mortality. A prompt, well-designed diagnostic workup is crucial. The investigations are chosen according to pretest diagnostic probabilities, estimated by the DIRECT approach: D stands for delay, or time since diagnosis; I for pattern of immune deficiency; R and T for radiological evaluation; E refers to clinical experience, and C to the clinical picture. Thorough familiarity with rapid diagnostic tests helps to decrease the use of bronchoscopy with bronchoalveolar lavage, which can cause respiratory status deterioration in those patients with hypoxemia. A prompt etiological diagnosis shortens the time on unnecessary empirical treatments, decreasing iatrogenic harm and costs. High-quality collaboration between intensivists and hematologists and all crossdisciplinary health care workers is paramount. All oxygen delivery systems should be considered to minimize invasive mechanical ventilation. Treatment of the malignancy is started or continued in the ICU under the guidance of the hematologists. The goal is to use the ICU as a bridge to recovery, with the patient returning to the hematology ward in sufficiently good clinical condition to receive optimal anticancer treatment.

Benefits of dexamethasone on early outcomes in patients with acute myeloid leukemia with hyperleukocytosis: a propensity score matched analysis

Hyperleukocytosis is associated with a significant early mortality rate in patients with acute myeloid leukemia (AML). To date, no controlled trial has ever evaluated a strategy to reduce this risk, and the initial management of these patients remains heterogeneous worldwide. The aim of the present study was to evaluate the influence of a short course of intravenous dexamethasone on the early outcomes of patients with hyperleukocytic AML with white blood cell (WBC) count above 50 × 10⁹/L. Clinical and biological data of all consecutive patients (1997-2017) eligible for intensive chemotherapy from a single center were retrospectively collected. A total of 251 patients with a median age of 51 years and a median WBC count of 120 × 10⁹/L were included, 95 of whom received dexamethasone. Patients treated with dexamethasone had higher WBC count and a more severe disease compared with those who did not, and they presented more often with leukostasis and hypoxemia, resulting in a more frequent need for life-sustaining therapies (p < 0.001). To account for these imbalances, patients were compared after adjusting for a propensity score, which included all variables with a prognostic influence in the overall cohort. In the matched cohort, dexamethasone was associated with lower early death (OR = 0.34, p = 0.0026) and induction failure rate (OR = 0.44, p = 0.02) and better overall survival (HR = 0.60, p = 0.011), with no impact on relapse risk (cHR = 0.73, p = 0.39). The overall survival benefit was confirmed among all tested subgroups. This study suggests that dexamethasone administration is safe and associated with a lower risk of induction mortality in patients with hyperleukocytic AML and deserves prospective evaluation.

Targeting SAMHD1 with hydroxyurea in first-line cytarabine-based therapy of newly diagnosed acute myeloid leukaemia: Results from the HEAT-AML trial

BACKGROUND

Treatment of newly diagnosed acute myeloid leukaemia (AML) is based on combination chemotherapy with cytarabine (ara-C) and anthracyclines. Five-year overall survival is below 30%, which has partly been attributed to cytarabine resistance. Preclinical data suggest that the addition of hydroxyurea potentiates cytarabine efficacy by increasing ara-C triphosphate (ara-CTP) levels through targeted inhibition of SAMHD1.

OBJECTIVES

In this phase 1 trial, we evaluated the feasibility, safety and efficacy of the addition of hydroxyurea to standard chemotherapy with cytarabine/daunorubicin in newly diagnosed AML patients.

METHODS

Nine patients were enrolled and received at least two courses of ara-C (1 g/m² /2 h b.i.d. d1-5, i.e., a total of 10 g/m² per course), hydroxyurea (1-2 g d1-5) and daunorubicin (60 mg/m² d1-3). The primary endpoint was safety; secondary endpoints were complete remission rate and measurable residual disease (MRD). Additionally, pharmacokinetic studies of ara-CTP and ex vivo drug sensitivity assays were performed.

RESULTS

The most common grade 3-4 toxicity was febrile neutropenia (100%). No unexpected toxicities were observed. Pharmacokinetic analyses showed a significant increase in median ara-CTP levels (1.5-fold; p = 0.04) in patients receiving doses of 1 g hydroxyurea. Ex vivo, diagnostic leukaemic bone marrow blasts from study patients were significantly sensitised to ara-C by a median factor of 2.1 (p = 0.0047). All nine patients (100%) achieved complete remission, and all eight (100%) with validated MRD measurements (flow cytometry or real-time quantitative polymerase chain reaction [RT-qPCR]) had an MRD level <0.1% after two cycles of chemotherapy. Treatment was well-tolerated, and median time to neutrophil recovery >1.0 × 10⁹ /L and to platelet recovery >50 × 10⁹ /L after the start of cycle 1 was 19 days and 22 days, respectively. Six of nine patients underwent allogeneic haematopoietic stem-cell transplantation (allo-HSCT). With a median follow-up of 18.0 (range 14.9-20.5) months, one patient with adverse risk not fit for HSCT experienced a relapse after 11.9 months but is now in second complete remission.

CONCLUSION

Targeted inhibition of SAMHD1 by the addition of hydroxyurea to conventional AML therapy is safe and appears efficacious within the limitations of the small phase 1 patient cohort. These results need to be corroborated in a larger study.

An effective and chemotherapy-free strategy of all-trans retinoic acid and arsenic trioxide for acute promyelocytic leukemia in all risk groups (APL15 trial)

The combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) has been demonstrated to have comparable effectiveness or better to ATRA and chemotherapy (CHT) in non-high-risk acute promyelocytic leukemia (APL). However, the efficacy of ATRA-ATO compared to ATRA-ATO plus CHT in high-risk APL remains unknown. Here we performed a randomized multi-center non-inferiority phase III study to compare the efficacy of ATRA-ATO and ATRA-ATO plus CHT in newly diagnosed all-risk APL to address this question. Patients were assigned to receive ATRA-ATO for induction, consolidation, and maintenance or ATRA-ATO plus CHT for induction followed by three cycles of consolidation therapy, and maintenance therapy with ATRA-ATO. In the non-CHT group, hydroxyurea was used to control leukocytosis. A total of 128 patients were treated. The complete remission rate was 97% in both groups. The 2-year disease-free, event-free survival rates in the non-CHT group and CHT group in all-risk patients were 98% vs 97%, and 95% vs 92%, respectively (P = 0.62 and P = 0.39, respectively). And they were 94% vs 87%, and 85% vs 78% in the high-risk patients (P = 0.52 and P = 0.44, respectively). This study demonstrated that ATRA-ATO had the same efficacy as the ATRA-ATO plus CHT in the treatment of patients with all-risk APL.

What Is Different in Acute Hematologic Malignancy-Associated ARDS? An Overview of the Literature

Background and Objectives: Acute hematologic malignancies are a group of heterogeneous blood diseases with a high mortality rate, mostly due to acute respiratory failure (ARF). Acute respiratory distress syndrome (ARDS) is one form of ARF which represents a challenging clinical condition. The paper aims to review current knowledge regarding the variable pathogenic mechanisms, as well as therapeutic options for ARDS in acute hematologic malignancy patients. Data collection: We provide an overview of ARDS in patients with acute hematologic malignancy, from an etiologic perspective. We searched databases such as PubMed or Google Scholar, including articles published until June 2022, using the following keywords: ARDS in hematologic malignancy, pneumonia in hematologic malignancy, drug-induced ARDS, leukostasis, pulmonary leukemic infiltration, pulmonary lysis syndrome, engraftment syndrome, diffuse alveolar hemorrhage, TRALI in hematologic malignancy, hematopoietic stem cell transplant ARDS, radiation pneumonitis. We included relevant research articles, case reports, and reviews published in the last 18 years. Results: The main causes of ARDS in acute hematologic malignancy are: pneumonia-associated ARDS, leukostasis, leukemic infiltration of the lung, pulmonary lysis syndrome, drug-induced ARDS, radiotherapy-induced ARDS, diffuse alveolar hemorrhage, peri-engraftment respiratory distress syndrome, hematopoietic stem cell transplantation-related ARDS, transfusion-related acute lung injury. Conclusions: The short-term prognosis of ARDS in acute hematologic malignancy relies on prompt diagnosis and treatment. Due to its etiological heterogeneity, precision-based strategies should be used to improve overall survival. Future studies should focus on identifying the relevance of such etiologic-based diagnostic strategies in ARDS secondary to acute hematologic malignancy.

Post-remission outcomes in AML patients with high hyperleukocytosis and inaugural life-threatening complications

Introduction

Patients with hyperleukocytic (HL) acute myeloid leukemia (AML) are at higher risk of early death. Initial management of these patients is challenging, not fully codified and heterogenous. Retrospective studies showed that several symptomatic measures might decrease early death rate but long-term data are scarce. We aimed to analyze whether the therapeutic measures carried out urgently at diagnosis may influence the outcome among HL AML patients having achieved who survived inaugural complications.

Methods

We retrospectively reviewed all medical charts from patients admitted to Saint-Louis Hospital between January, 1^st 1997 and December, 31st 2018 with newly diagnosed AML and white blood cell (WBC) count above 50x10⁹/L. Outcome measures were cumulative incidence of relapse (CIR), treatment-related mortality (TRM) defined as relapse-free death, and overall survival. Univariate and multivariate analyses were performed using Cox proportional hazards models.

Results

A total of 184 patients with HL AML in complete remission (CR) were included in this study. At 2 years after CR. 62.5% of patients were alive, at 5 years, cumulated incidence of relapse was 55.8%. We found that every therapeutic measure, including life-sustaining therapies carried out in the initial phase of the disease, did not increase the relapse risk. The use of hydroxyurea for more than 4 days was associated with a higher risk of relapse. At the end of the study, 94 patients (51.1%) were still alive including 23 patients out of 44 aged less than 60 yo that were able to return to work.

Conclusion

We show that the use of emergency measures including life sustaining therapies does not come at the expense of a higher risk of relapse or mortality, except in the case of prolonged use of hydroxyurea. Patients with HL AML should be able to benefit from all available techniques, regardless of their initial severity.

Effectiveness and safety of leukapheresis in hyperleukocytic leukemias: a retrospective multicenter study

Leukapheresis is an effective adjuvant therapy for leukemia patients with hyperleukocytosis, but few studies have reported recent data with modern modalities and comparisons among different leukemia types. We conducted a retrospective study on leukapheresis among 420 patients with AML, ALL and CML in four local centers. WBC counts decreased significantly (p < 0.001) postleukapheresis in all three cohorts. Clearance efficiency was higher in acute leukemia patients than CML patients (p < 0.01). Concomitant leukocytoreduction drugs improved WBC reduction only in AML patients (p < 0.05). Leukocyte, hemoglobin and platelet levels preleukapheresis might affect the clearance efficiency in AML and/or ALL patients. Hematological toxicities were the major concerns, but most of them were mild, and only 11 patients died of all causes within one week postleukapheresis. In conclusion, leukapheresis can safely reduce the leukemic burden, especially for patients with acute leukemias.

Acute Myeloid Leukemia Complicated by Hyperleukocytosis and Leukostasis in the Emergency Department

Acute myeloid leukemia (AML) and other hematologic malignancies can be complicated by hyperleukocytosis, which leads to an increased risk for other severe complications such as tumor lysis syndrome, disseminated intravascular coagulation (DIC), and leukostasis. In this report, we present a case of a 65-year-old female with newly diagnosed AML complicated by leukostasis. We briefly review the clinical significance as well as initial diagnostic and therapeutic considerations pertaining to hyperleukocytosis and its associated complications.

Acute myeloid leukemia with hepatic infiltration presenting as obstructive jaundice

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Acute myeloid leukemia can present as cholestasis with obstructive jaundice.

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Extramedullary leukemia infiltration of liver can delay initiation of chemotherapy.

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Hydroxyurea may be employed as a temporizing measure for effects of hyperleukocytosis.

We present the case of a 55-year-old woman who presented with laboratory studies concerning for acute myeloid leukemia (AML) as well as obstructive cholestasis. In similar previously reported cases, concerns of chemotherapy toxicity exacerbated by liver dysfunction or concerns of untreated, concurrent cholecystitis in a neutropenic patient often delay initiation of chemotherapy for full medical workup. At admission, our patient was started on the cytoreductive agent hydroxyurea. By day 10 of her medical workup, her liver function had improved with total bilirubin levels normalizing. At that time, full-dose 7 + 3 induction with cytarabine and daunorubicin was then initiated.

Outcomes of Sepsis and Septic Shock in Cancer Patients: Focus on Lactate

The number of oncological patients (OP) admitted to intensive care units (ICU) for sepsis/septic shock has dramatically increased in recent years. The definition of septic shock has been modified, adding hyperlactatemia as a severity biomarker for mortality. However, it remains poorly reported in septic OP. We performed a retrospective analysis from a prospective database of sepsis/septic shock patients admitted to our ICU between September 2017 and September 2019 and followed until day 90. We identified 251 patients and 31.9% had active oncological comorbidity, mainly solid tumor (81.3%). Septic shock criteria were met for 112 (44.6%). Hyperlactatemia was observed in 136 (54.2%) patients and this was associated with a lower survival rate. Overall 90-day mortality was 15.1%. In OP vs. non-OP, hyperlactatemia was more frequent (65% vs. 49.1%, p = 0.013) and associated with lower survival (65.4% vs. 85.7%, p = 0.046). In OP, poor performance status was also associated with lower survival (HR 7.029 [1.998-24.731], p = 0.002) In an adjusted analysis, cancer was associated with lower 90-day survival (HR 2.690 [1.402-5.160], p = 0.003). In conclusion, septic OP remains a high mortality risk group in whom lactate levels and performance status could help with better risk stratification.

Clinical Implications of Inflammation in Acute Myeloid Leukemia

Recent advances in the description of the tumor microenvironment of acute myeloid leukemia, including the comprehensive analysis of the leukemic stem cell niche and clonal evolution, indicate that inflammation may play a major role in many aspects of acute myeloid leukemia (AML) such as disease progression, chemoresistance, and myelosuppression. Studies on the mechanisms of resistance to chemotherapy or tyrosine kinase inhibitors along with high-throughput drug screening have underpinned the potential role of glucocorticoids in this disease classically described as steroid-resistant in contrast to acute lymphoblastic leukemia. Moreover, some mutated oncogenes such as RUNX1, NPM1, or SRSF2 transcriptionally modulate cell state in a manner that primes leukemic cells for glucocorticoid sensitivity. In clinical practice, inflammatory markers such as serum ferritin or IL-6 have a strong prognostic impact and may directly affect disease progression, whereas interesting preliminary data suggested that dexamethasone may improve the outcome for AML patients with a high white blood cell count, which paves the way to develop prospective clinical trials that evaluate the role of glucocorticoids in AML.

High dose cyclophosphamide for cytoreduction in patients with acute myeloid leukemia with hyperleukocytosis or leukostasis

Hyperleukocytosis may lead to multiple medical emergencies. Hydroxyurea, intensive chemotherapy, and leukapheresis are used for cytoreduction. However, there is little data regarding the best approach. Here, we report on the efficacy and safety of high dose cyclophosphamide (HDCy; 60 mg/kg). 27 patients with acute myeloid leukemia or blast phase chronic myeloid leukemia who presented with white blood cell count (WBC) of ≥50x10⁹/L or symptoms of leukostasis were treated with HDCy. Primary endpoint was early mortality (death within seven days of admission). Median WBC was 107 × 10⁹/L at time of HDCy; 74% had leukostasis symptoms at presentation. Eight (29.6%) patients died within seven days of admission. Sustained WBC reduction was achieved in 18/24 (75%) evaluable patients with median nadir of 0.25 × 10⁹/L. Adverse effects attributed to HDCy included tumor lysis syndrome (n = 7; 25.9%), disseminated intravascular coagulopathy (n = 5; 18.5%), and hemorrhagic cystitis (n = 1; 3.7%). HDCy was effective for cytoreduction and adverse effects were acceptable.

Acute Myeloid Leukemia: Advanced Practice Management From Presentation to Cure

Acute myeloid leukemia (AML) is the most common acute leukemia in adults, diagnosed in approximately 21,450 individuals annually in the US with nearly 11,000 deaths attributable to this disease (National Cancer Institute, 2020). Acute myeloid leukemia is a disease of the elderly, with the average age of diagnosis being 68 years old (Kouchkovsky & Abdul-Hay, 2016). It is a heterogeneous disease with widely varying presentations but universally carries a poor prognosis in the majority of those affected. Unfortunately, the 5-year overall survival rate remains poor, at less than 5% in patients over 65 years of age (Thein, Ershler, Jemal, Yates, & Baer, 2013). The landscape of AML is beginning to change, however, as new and improved treatments are emerging. Advanced practitioners (APs) are often involved in the care of these complex patients from the time of initial symptoms through diagnosis, treatment, and potentially curative therapy. It is vitally important for APs to understand and be aware of the various presentations, initial management strategies, diagnostic workup, and treatment options for patients with AML, especially in the elderly population, which until recently had few treatment options. This Grand Rounds article highlights the common presenting signs and symptoms of patients with AML in the hospital, including a discussion of the upfront clinical stability issues, oncologic emergencies, diagnostic evaluation, and current treatment options for elderly patients and those with poor performance status.

Oncologic Emergencies: Traditional and Contemporary

The recognition and management of oncologic emergencies are becoming increasingly relevant in the intensive care unit, particularly in the era of novel biologic therapies. Early recognition and multidisciplinary collaboration are essential to improving patient outcomes. This article discusses aspects of diagnosis and management for important malignancy-associated emergencies.

Leukocytapheresis for patients with acute myeloid leukemia presenting with hyperleukocytosis and leukostasis: a contemporary appraisal of outcomes and benefits

Introduction: Hyperleukocytosis, defined as a total white blood cell count (WBC) >50 or more commonly >100 × 10⁹ cells/L, is a presenting feature of acute myeloid leukemia (AML) in about 6-20% of cases and is associated with a higher risk of tumor lysis syndrome (TLS), disseminated intravascular coagulation (DIC), clinical leukostasis with end organ damage, and mortality.Areas covered: In this review, authors discuss the implications of hyperleukocytosis in AML and the current understanding of cytoreductive strategies with a focus on the use of leukocytapheresis.Expert commentary: Efforts to rapidly reduce peripheral myeloblasts have included the use of leukocytapheresis. Early studies demonstrated feasibility in reducing peripheral WBC and blast counts as well as clinically relevant patient outcomes which prompted its common use for many years. However, more recent data have directly challenged the previously touted reports of reduced TLS and DIC incidence as well as survival benefit, even in patients with clinical leukostasis. The use of leukocytapheresis remains highly controversial with wide practice variations among physicians, institutions, and countries given the lack of high-quality data, risks associated with leukocytapheresis itself, associated high costs, resource utilization, and lack of evidence-based clinical guidelines.

Ribonucleotide reductase inhibitors suppress SAMHD1 ara-CTPase activity enhancing cytarabine efficacy

The deoxycytidine analogue cytarabine (ara-C) remains the backbone treatment of acute myeloid leukaemia (AML) as well as other haematological and lymphoid malignancies, but must be combined with other chemotherapeutics to achieve cure. Yet, the underlying mechanism dictating synergistic efficacy of combination chemotherapy remains largely unknown. The dNTPase SAMHD1, which regulates dNTP homoeostasis antagonistically to ribonucleotide reductase (RNR), limits ara-C efficacy by hydrolysing the active triphosphate metabolite ara-CTP. Here, we report that clinically used inhibitors of RNR, such as gemcitabine and hydroxyurea, overcome the SAMHD1-mediated barrier to ara-C efficacy in primary blasts and mouse models of AML, displaying SAMHD1-dependent synergy with ara-C. We present evidence that this is mediated by dNTP pool imbalances leading to allosteric reduction of SAMHD1 ara-CTPase activity. Thus, SAMHD1 constitutes a novel biomarker for combination therapies of ara-C and RNR inhibitors with immediate consequences for clinical practice to improve treatment of AML.

Novel tumor-suppressor FOXN3 is downregulated in adult acute myeloid leukemia

Forkhead box protein N3 (FOXN3) is a transcriptional repressor involved in cell cycle regulation and tumorigenesis. Abnormalities in gene structure and epigenetics of FOXN3 are closely associated with the occurrence of hematological malignancies; however, its involvement in the pathogenesis of acute myeloid leukemia (AML) remains unknown. The present study aimed to examine the potential significance of FOXN3 in AML. FOXN3 expression levels were examined in patients with AML and AML cell lines, and its clinical significance in AML was evaluated. FOXN3-overexpressing AML cell lines were established, and the biological function of FOXN3 was detected by flow cytometry and a Cell Counting Kit-8 assay. A significant decrease in FOXN3 expression levels was observed in patients with AML and in the AML cell lines in vitro. FOXN3 expression levels were associated with the number of leukocytes in patients. FOXN3 overexpression may inhibit cell proliferation in AML cell lines, induce cell cycle S-phase arrest and promote apoptosis in OCI-AML3 and THP-AML cells. The present study provided insight into how FOXN3 may serve as a novel tumor suppressor in AML.

Dose-related mucositis with hydroxyurea for cytoreduction in acute myeloid leukemia

Hyperleukocytosis occurs in 15–20% of all newly diagnosed acute myeloid leukemia patients and requires emergent treatment with leukapheresis or hydroxyurea when accompanied by signs or symptoms of leukostasis. Currently, there is no standardized hydroxyurea dosing strategy, although usual dosing ranges from 50 to 150 mg/kg/day, and prescribing patterns vary significantly among oncologists and institutions. In addition to other hematologic and dermatologic toxicities, the use of hydroxyurea may be associated with significant mucositis and mucositis-related pain. The purpose of this study was to compare mucositis-related pain between two different hydroxyurea dosing strategies in patients who received hydroxyurea for cytoreduction during induction. A retrospective chart review of adult patients with acute myeloid leukemia treated with chemotherapy at UNC Medical Center from April 2014 to April 2016 who received at least one dose of hydroxyurea for cytoreduction was conducted. This study compared the safety and toxicity profiles of hydroxyurea in patients who received high-dose hydroxyurea (≥75 mg/kg/day) versus low-dose hydroxyurea (<75 mg/kg/day). Safety and toxicity were evaluated based on indicators of mucositis and cumulative intravenous narcotic requirements following induction chemotherapy. Data collection included baseline demographics, mucositis risk factors, baseline laboratory values, hydroxyurea dosing, mucositis indicators, and pain indicators. A total of 55 patients were included in the study, 21 patients (38.2%) received the high-dose hydroxyurea dosing strategy. The high-dose hydroxyurea dosing strategy had a significantly higher white blood cell count at diagnosis, increased duration of hydroxyurea, and received a higher cumulative dose of hydroxyurea. Additionally, the high-dose hydroxyurea dosing strategy patients were associated with significantly more grade 3 or 4 mucositis requiring a formulation change (0% versus 28.6%, p = 0.002) and significantly higher cumulative intravenous narcotic requirements during induction (p = 0.019). No significant differences in baseline demographics or mucositis risk factors between dosing strategies were identified. The high-dose hydroxyurea dosing strategy patients had a significant increase in cumulative intravenous narcotic requirements and formulation changes, both common interventions made for the treatment of mucositis. Additional studies are needed to further elucidate the safety and toxicity profiles of hydroxyurea dosing strategies and to explore the correlation between total cumulative hydroxyurea dose and total cumulative narcotic requirements.

Effect of leukapheresis on blood coagulation in patients with hyperleukocytic acute myeloid leukemia

INTRODUCTION

Leukapheresis has been proposed to reduce white blood cell (WBC) count in hyperleukocytic acute myeloid leukemia (AML). However, no survival benefit has been proven and leukapheresis can potentially affect coagulation and worsen bleeding and disseminated intravascular coagulation (DIC). We analyzed the effect of leukapheresis on coagulation tests in a cohort of hyperleukocytic AML patients.

METHODS

Retrospective chart review of hyperleukocytic AML patients who underwent leukapheresis between 2003 and 2014. Blood coagulation tests (platelets, PT, INR, aPTT, fibrinogen, D-Dimers and fibrin degradation products (FDP)) were collected before and after each procedure and DIC score was computed. Transfusions of platelets and coagulation factors were collected.

RESULTS

Ninety patients and 129 leukapheresis sessions were screened. After exclusion of the sessions associated with transfusions, we observed in 44 patients a significant decrease in platelets (from 75.69±89.48 to 44.59±47.71.10⁹/L, p=0.001) and fibrinogen (from 4.05±1.29 to 3.35±1.37g/L, p<0.0005) along with an increase in PT (from 14.62±2.73 to 15.62±3.63s, p=0.001), aPTT (from 33.70±6.32 to 39.24±13.53s, p=0.009) and INR (from 1.33±0.2 to 1.45±0.34, p=0.002) after the first procedure. Bleeding complications, all intracerebral hemorrhages, were documented in 3 patients within 24h of leukapheresis. After combining 73 repeat procedures, we observed similar significant results except for the aPTT prolongation. The platelets and PT components of the DIC score, but not the fibrinogen component, were significantly increased after leukapheresis.

CONCLUSIONS

In hyperleukocytic AML patients, leukapheresis is associated with clinically significant decreases in platelets and fibrinogen and prolonged clotting times.